The influence of family functioning on adolescents’ experiences with bullying is well-documented; however, the mechanisms underlying this relationship require further exploration. The present study examined whether difficulties in emotion regulation mediate the association between family functioning and bullying involvement among high school students. This research employed a descriptive-correlational design. The target population included all high school students in Birjand, Iran. Using a multi-stage cluster sampling method, a total of 350 students (M_age = 14.22, SD = 4.48) were selected during the 2023–2024 academic year. Illinois Bullying Scale (IBS), Difficulties in Emotion Regulation Scale – 16 item version (DERS-16), and Family Assessment Device (FAD) were used for data collection. Data were analyzed using SPSS version 24.0 and AMOS software. The results indicated that poorer family functioning was significantly associated with higher levels of both bullying perpetration and victimization. Moreover, emotion regulation difficulties significantly mediated the relationship between family functioning and bullying experiences (p < .001). These findings highlight the critical role of family dynamics and emotional regulation in shaping adolescents' involvement in bullying behaviors. Intervention programs that focus on strengthening family functioning and enhancing adolescents’ emotion regulation skills may be effective in mitigating bullying and its associated psychological consequences.